What Is Tricompartmental Osteoarthritis?

Knee osteoarthritis can involve any of the three compartments

Exam for tricompartmental knee osteoarthritis.
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Osteoarthritis affects the knee joint more than any other joint. The knee joint contains four bones—femur, tibia, patella, and fibula—and three compartments. Osteoarthritis can affect one, two, or all three of those compartments. When all three are affected, it is called tricompartmental osteoarthritis.

What Are the Three Compartments of the Knee?

Each of the three compartments is named after the two bones that join together within the compartment.

They are:

  • Medial femoro-tibial compartment (the inside compartment
  • Lateral femoro-tibial compartment (the outside compartment)
  • Patellofemoral compartment (the kneecap and femur)

Examining the Knee Compartments

Physical exam

A physical examination may provide the first indication of which compartment is affected. Your doctor will ask you to stand and to walk. While standing, your doctor will observe you for any postural deformity, such as valgus (knock-kneed) or varus (bow-legged) deformity. There may also be obvious or subtle differences in leg length.

When you are asked to walk, your doctor will observe gait abnormalities, such as limping, shuffling, or being unable to walk. Your doctor also will check for signs of joint laxity and check your range of motion. Your doctor will also observe the knee for joint effusion, palpate the knee when in a flexed position, as well as check for signs of muscle atrophy and skin changes.

Imaging studies

X-rays will be needed to confirm cartilage loss and joint damage associated with the abnormalities observed during your physical examination. On x-ray imaging, cartilage loss shows up as narrowing of the space between the ends of the bones forming the joint. This is referred to as joint space narrowing.

Often, the narrowing of the joint space appears on one side. Medial narrowing is observed in 75 percent of people who have knee osteoarthritis and it can cause a bow-legged stance and gait. Lateral narrowing, which is less common in people with knee osteoarthritis, is associated with a knock-kneed stance and gait. Close to half of all knee osteoarthritis patients have evidence of patellofemoral damage on x-rays.

Conservative Treatment of Tricompartmental Knee Osteoarthritis

Treatment options for knee osteoarthritis depend on severity of joint damage, pain level, and activity level. Before surgical options are considered, non-surgical treatments should be considered and possibly tried, including:

  • Medications - This is traditional treatment, aimed at controlling pain and managing other osteoarthritis symptoms. Drugs to slow disease progression are still lacking.
  • Exercise - Low impact exercise helps to preserve strength and range of motion of affected joints.
  • Weight management - Carrying extra pounds adds force to your joints as you move. That is exactly the burden you want to avoid with knee osteoarthritis.   
  • Topical pain relievers - Topical creams, gels, and ointments provide alternative pain relief for people who have had an inadequate response or cannot tolerate oral medications.
  • Lateral wedge insoles - Special insoles are designed to help reduce pain associated with medial knee osteoarthritis by changing mechanics of the knee.
  • Viscosupplementation - A series of knee injections with a gel-like substance (hyaluronates) is used to supplement the properties of synovial fluid in knees affected by osteoarthritis.
  • Intra-articular steroid injections - An injection into the affected knee joint with a corticosteroid medication is performed to reduce inflammation and pain.
  • Dietary Supplements - Several supplements are marketed for joint health. While they are generally considered safe, their effectiveness has not been proven.

Surgical Replacement of Affected Knee Compartments

When conservative treatments yield inadequate results, the next step may be surgery. Arthroscopic debridement or osteotomy may be considered appropriate in certain cases, prior to considering total knee replacement.

When only one knee compartment is involved, your doctor and orthopedic surgeon may recommend a partial knee replacement or unicompartmental knee replacement, rather than a total knee replacement. Although the decision to have a partial knee replacement may seem reasonable and straightforward, there are factors to consider.

It may be just a matter of time before the other compartments wear out and more surgery is needed. Would it be better to have a total knee replacement rather than a partial knee replacement and be faced with potential surgery in the future? Your doctor will assess the severity of your condition and recommend the best course for your individual case.

Besides a unicompartmental knee replacement or a total knee replacement, there is also a bicompartmental knee replacement. The bicompartmental knee replacement is an option for people with knee osteoarthritis of the medial and patellofemoral compartments. Compared to total knee replacement, the unicompartmental and bicompartmental knee replacements preserve normal bone and the two cruciate ligaments.

A Word From Verywell

Most people with knee osteoarthritis have unequal involvement of the three knee compartments. Treatment options, especially surgical options, depend on whether you have unicompartmental, bicompartmental, or tricompartmental knee osteoarthritis.

Knee pain is a common medical complaint which takes people to their primary doctor for an initial evaluation. An accurate diagnosis is essential to managing knee osteoarthritis. Appropriate treatment follows the diagnosis. An orthopedic specialist may ultimately be needed to optimize the treatment plan. There are numerous conservative treatments to try. When it is time to consider surgery, find the best orthopedic surgeon available to you.

Sources:

Beutler, Anthony, MD et al. Physical Examination of the Knee. UpToDate. Updated April 13, 2017.

Deveza, Leticia Alle, MD, et al. Management of Knee Osteoarthritis. UpToDate. Updated April 17, 2017.

Lane, Nancy E. and  Wallace, Daniel J. All About Osteoarthritis. The Lower Body. Pages 102-105. Oxford University Press. 2002.

Sabatini, Luigi et al. Bicompartmental Knee Arthroplasty.Annals of Translational Medicine. 2016 Jan; 4(1): 5.

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